Structural insulated panel (sip) for a modular building

ABSTRACT

A structural insulated panel, SIP, (101) for a building (100) in which the SIP is attachable to another such SIP (101) to provide a structure of the building (100). The SIP (101) comprises a frame (200), a first board (208) attached to a first face of the frame (200), a second board (209) attached to a second face of the frame (200) and an insulating layer (401) bounded by the frame (200) and the first (208) and second boards (209). The frame (200) is fibre-reinforced plastic, FRP. The frame (200) has a joining surface that faces away from the centroid of the SIP (101) so as to be mateable with a joining surface of a frame of another such SIP (101).

FIELD OF THE DISCLOSURE

The present disclosure relates to a Structural Insulated Panels (SIPs) for a modular building. The disclosure relates particularly, but not exclusively, applicable to a SIP with a fibre-reinforced plastic (FRP) frame.

BACKGROUND TO THE DISCLOSURE

Structural Insulated Panels (SIPs) provide a quick and efficient way of constructing modular buildings. SIPs are usually manufactured offsite and assembled onsite. Generally, SIPs comprise an insulating layer sandwiched between two structural outer boards. The structural outer boards provide the primary load path within each SIP. The SIPs are mounted to a frame that provides additional structural support to the building. The structural outer boards are generally made from plywood. The insulating core provides most of the insulation.

The frame to which the SIPs are moulded often comprises wood or metal, as these are common building materials and are relatively cheap and simple to erect onsite. However, the wooden frames have poor defence against moisture and fire. The metal frames are susceptible to rust and have poor insulating properties. The high conductivity of the metal frames can also lead to “cold bridging” which results in damp patches forming on the inside of the building at the location of the frame. Additionally, the frame is assembled onsite around the SIPs which results in increased labour time. Furthermore, the SIPs and frame members are commonly coupled using metal screws or bolts which are also likely to rust.

The present disclosure seeks, amongst other things, to overcome these problems.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the disclosure, there is provided a structural insulated panel, SIP, for a modular building, the SIP being attachable to another such SIP to provide a structure of the modular building, the SIP comprising:

a frame;

a first board attached to a first face of the frame;

a second board attached to a second face of the frame; and

an insulating layer bounded by the frame and the first and second boards,

wherein the frame is fibre-reinforced plastic, FRP.

Optionally, the frame has a joining surface that faces away from the centroid of the SIP so as to be mateable with a joining surface of a frame of another such SIP.

Optionally, the joining surface extends around the entire perimeter of the SIP.

Optionally, the frame comprises at least two edge members located at periphery of the SIP, at least one of the at least two edge members providing at least a part of the joining surface and at least one brace member extending from one of the at least two edge members to another one of the at least two edge members to provide support to those edge members.

Optionally, the at least part of the joining surface provided by the at least one edge member is flat, and preferably wherein the at least part of the joining surface provided by the at least one edge member is either perpendicular or parallel to the first and/or second face of the frame.

Optionally, the at least two edge members comprise:

a base member;

a first side member;

a second side member; and

a top member.

Optionally, the brace member is parallel to the first side member and to the second side member.

Optionally, the brace member is oblique to the first side member or the second side member.

Optionally, the frame further comprises at least one bar member.

Optionally, the bar member is parallel to the base member and/or to the top member.

Optionally, the first board is attached to the first face of the frame at the bar member and the second board is attached to the second face of the frame at the bar member. The first board and/or the second board may have an edge aligned with the bar member, such that the first board and/or the second board do(es) not extend over the first face and/or second face respectively in one direction from the bar member to a/the periphery of the frame.

Optionally, the at least two edge members and/or the at least one brace member and/or the at least one bar member have a square or rectangular cross section.

Optionally, the at least two edge members and/or the at least one brace member and/or the at least one bar member are hollow, and have a depth between 75 mm to 300 mm and a width between 25 mm to 200 mm.

Optionally, wherein the at least two edge members and/or the at least one brace member and/or the at least one bar member are joined to one another using adhesive.

Optionally, the frame is pultruded FRP.

Optionally, the first board and the second board do not extend the full height of the frame.

Optionally, the SIP further comprises a flooring truss attached to the first face of the frame in the area not covered by the first board.

Optionally, the first board and the second board each comprise a magnesium oxide board.

Optionally, the first board and the second board are each between 3 mm to 25 mm thick.

Optionally, the first board and the second board each coupled to the frame using adhesive.

Optionally, the insulating layer comprises a non-combustible mineral wool.

Optionally, the insulating layer is between 50 mm to 250 mm thick.

Optionally, the panel further comprises a fire resistant layer; the fire resistant layer is sandwiched between the frame and the first board.

Optionally, the fire resistant layer comprises an intumescent material such as soft char or hard char.

Optionally, the panel further comprises an outer covering; the outer covering is applied to the second board.

Optionally, the outer covering comprises a water resistant material, such as a silicone render.

Optionally, the panel further comprises an inner covering; the inner covering is applied to the first board.

Optionally, the inner covering comprises a fire resistant material, such as soft char or hard char.

According to a further aspect of the disclosure, there is provided a structural insulated panel assembly, comprising the structural insulated panel described above joined to another such structural insulated panel.

Optionally, the SIPs are joined to one another at the joining surfaces using adhesive.

Optionally, the adhesive comprises a two-part methacrylate adhesive.

Embodiments of the disclosure are now described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a building according to an embodiment of the disclosure.

FIG. 2 is a schematic perspective view of a SIP of the embodiment.

FIG. 3 is a schematic side view of a frame of the SIP.

FIG. 4A is a schematic side view of the SIP.

FIG. 4B is a schematic cross-sectional view of the SIP along the line B-B in FIG. 4A.

FIG. 4C is a magnified schematic cross-sectional view of the SIP at the location C shown in FIG. 4B showing the layers of the SIP.

FIG. 5 is a schematic side view of the SIP assembly comprising two SIPs joined to one another vertically.

FIGS. 6A and 6B are schematic top views of the SIP assembly comprising two SIPs being joined to one another in a corner joint.

FIGS. 7A and 7B are schematic cross-sectional views of the SIP assembly comprising two SIPs being joined to one another in a corner joint.

FIGS. 8A and 8B are schematic top views of the SIP assembly comprising two SIPs being joined to one another in a T section joint.

FIGS. 9A and 9B are schematic cross-sectional views of the SIP assembly comprising two SIPs being joined to one another in a T section joint.

FIGS. 10A and 10B are schematic top views of the SIP assembly comprising two SIPs being joined to one another in a double T section joint.

FIGS. 11A and 11B are schematic cross-sectional views of the SIP assembly comprising two SIPs being joined to one another in a double T section joint.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to FIG. 1 , a building 100 comprises a plurality of Structural Insulated Panels (SIPs) 101. The SIPs 101 can be coupled to one another to form a SIP assembly 500 comprising at least two SIPs 101. The combination of a number of SIP assemblies 500 provides a wall 102. In the particular embodiment illustrated in FIG. 1 , the walls 102 comprise four identical SIPs 101 in a two-by-two arrangement so as to provide a two storey building. The SIPs 101 are also arranged in line with each other. However, the SIPs 101 can be a range of sizes and arranged in a number of ways so as to meet the shape and dimension requirements of the construction brief. The SIPs 101 can be used for internal and external walls 102. The SIPs 101 can be used for low rise structures which may be as tall as 18 m depending on the composition of the structural components.

In FIG. 1 a roof 103 is shown. The roof 103 can also be made using a SIP 101 or can be made using conventional means. The roof 103 aims to provide a closed structure for the building 100 so that it is substantially airtight. It should be noted that the building 100 is significantly simplified for the purposed of clarity and any real building 100, such as the low rise structure mention above, could comprise significantly more SIPs 101. However, the general structure of the building 100, as outlined in FIG. 1 , would likely apply to all buildings 100.

An embodiment of the SIP 101 is shown in FIG. 1 , and a frame 200 of the SIP is shown in FIG. 2 , that is the SIP 101 with a first board 208 and a second board 209 not in place. The frame 200 is shown to provide a rectangular outer shape, however, it is also possible for the frame to provide a number of shapes including square, triangular or trapezoidal depending on the design requirements.

The frame 200 has a joining surface that faces away from the centroid of the SIP 101 so as to be mateable with a joining surface of a frame 200 of another such SIP 101. The joining surface extends around the entire perimeter of the SIP 101. The frame 200 comprises at least two edge members located at periphery of the SIP 101, at least one of the at least two edge members providing at least a part of the joining surface, and at least one brace member 205 extending from one of the at least two edge members to another one of the at least two edge members to provide support to those edge members. It is preferable that the joining surface is provided by the frame 200 as the frame 200 is normally the primary structural load path.

At least part of the joining surface provided by the at least one edge member is flat. Preferably, the at least part of the joining surface provided by the at least one edge member is either perpendicular or parallel to the first and/or second face of the frame 200. Providing a flat surface on the frame 200 eases the assembly process of the SIPs 101 onsite.

The at least two edge members of the frame 200 comprises a base member 201, a top member 202, a first side member 203 and a second side member 204. FIG. 2 also shows a number of brace members 205 and two bar member members 206. The brace members 205 provide additional structural support to the frame 200 in relation to both static loading and wind loading. The bar members 206 are preferably used for coupling the first board 208 and the second board 209 to the frame 200. However, it is also possible and preferable, as it may provide additional strength, to couple the first board 208 and the second board 209 to the brace members 205 as well as the bar members 206.

The brace members 205 shown in FIG. 3 are identical to the first side member 203 and the second side member 204. However, it can be appreciated that the brace members 205 may differ in shape, size or structure to the first side member 203 and the second side member 204 depending on the structural loading requirements. Additionally, in FIG. 3 , the brace members 205 are parallel and the bar members 206 are perpendicular to the first side member 203 and the second side member 204, however, it is also possible for the brace members 205 and bar members 206 to be oblique to the first side member 203 and the second side member 204 .

The bar members 206 in FIG. 2 are shown to comprise a number of sections in between each of the brace members 205; however, it is also possible for the bar members 206 to comprise a single section.

The frame 200 preferably comprises a Fibreglass Reinforced Plastic material (FRP), although other composite materials may also be suitable. The FRP frame 200 can reduce the chances of rusting as well as reducing the overall thermal conductivity of the SIP 101 (explained below). In this particular embodiment the frame 200 is made from either Grade E23 or E17 FRP and is manufactured by a certified supplier in accordance with BS EN13706.

The FRP frame 200 is preferably manufactured using pultrusion, although, other manufacturing processes may also be suitable. The pultrusion process involves pulling fibreglass, or other suitable fibres, through a bath of polymer resin. The fibres are then impregnated into the resin using heat or pressure. A continuous flow of FRP is cut to the required length at the end of the manufacturing process. The pultrusion process aims to align the fibres in a substantially unidirectional orientation along the length of the frame 200 member so as to provide a good compressive strength. This may be particularly useful for the strength of the upright members, such as the first side member 203, the second side member 204 and the brace members 205.

The members of the frame 200 are preferably coupled to one another using an adhesive. However, it may also be possible for the frame 200 members to be coupled to one another using mechanical fastening means, such as screws, nails and nuts and bolts. Although, metal mechanical fastening means could be susceptible to rusting in moist conditions. The adhesive 207 may preferably comprise a two-part methacrylate adhesive, although any suitable adhesive for building construction may be used.

It is preferable for the frame 200 to comprise a square or rectangular cross section along the length of the member, although, it is also possible for other cross sections such as X, I and T cross sections. In this embodiment the frame 200 cross section is rectangular as this is best suited for joining to the flat boards 208 209 and other frame 200 members. It is also shown, in more detail in FIG. 4 , that the frame 200 comprises a hollow cross section. This improves the thermal efficiency as the hollow cavity in the frame 200 can be filled with an insulating filler 402.

In the embodiment shown in FIGS. 2 and 3 , the frame 200 height is preferably between 1.5 to 5 m. The width of the frame 200 is preferably between 2 m to 15 m. The brace members 205 are typically placed between 0.3 m and 1.2 m depending on the structural requirements of the building 100. The bar members 206 are typically placed between 1.2 m to 3 m apart of which the spacing is generally defined by the height of the first board 208 and the second board 209. The depth of the frame 200 is preferably between 75 mm to 300 mm depending on the structural requirements of the building 100 and the specifications of the other layers (more detail below). The width of the frame 200 members is preferably between 25 mm to 200 mm depending on the structural requirements of the building 100 (more detail below). The measurements mentioned above are simply to give an idea of the normal working dimensions of the frame. The frame 200 size is flexible and can be adjusted to suit the design requirements. The overall size of the frame 200 is generally limited by the transportation vehicle to the building site, the lifting equipment at the site and the space at the site. For example, for smaller sites the SIP 101 can be manufactured in smaller width sections and assembled on site. In particular, the smaller sections of the SIP 101 may be used to allow for small changes in wall line, for alcoves or to join service risers. The assembly process can use the same adhesive 207 as used in the manufacturing process or a more suitable adhesive 207 for site conditions may be used.

In FIG. 2 , the SIP 101 is shown with the first board 208 and the second board 209 attached to the frame 200. The first board 208 is attached to the first face of the frame 200 and the second board 209 is attached to the second face of the frame 200. The insulating layer 401 is not shown in FIG. 3 . The first board 208 and the second board 209 are coupled to the frame 200 on either side so as to sandwich the frame 200. The frame 200 is preferably the primary load carrier and the first board 208 and the second board 209 may provide additional racking strength.

In an embodiment shown in FIGS. 2 and 3 , the first board 208 and the second board 209 do not cover the full height of the frame 200. The gaps at the top and bottom of the frame 200, which extend from each bar member 206 to the edge of the frame 200, are provided to give space for the fitting of floors and ceilings, which can allow the floor or ceiling to directly couple to the frame. This can improve the overall strength of the building 100 as the frame 200 is preferably the primary load carrier. In other embodiments, it is possible for the first board 208 and the second board 209 to extend the full height of the frame 200 and the floor or ceiling is attached directly to the first board 208 or the second board 209.

It is preferable that the first board 208 and the second board 209 are coupled to the frame 200 using an adhesive 207. However, it may also be possible for the frame 200 members to be coupled to one another using mechanical fastening means, such as screws, nails and nuts and bolts. Although, metal mechanical fastening means could be susceptible to rusting in moist conditions. The adhesive 207 may preferably comprise a two-part methacrylate adhesive, although any suitable adhesive for building construction may be used. Nevertheless, the SIP 101 can provide a closed structure that is substantially airtight so as to maximise the insulating properties. It may be possible for the building 100 to achieve an air tightness performance as low as 5 m³/hr/m² at 50 Pa.

The first board 208 and the second board 209 are preferably made from Magnesium Oxide Board (MgO). The MgO board 208 209 can be readily recycled and can provide a high level of fire resistance. It is also possible to use other board 208 209 materials, such as plywood, depending on the requirements for the building 100. The first board 208 and the second board 209 are typically between 3 mm and 25 mm thick depending on the structural and insulation requirements of the building 100.

FIG. 4A shows the SIP 101, as shown in FIG. 3 , from the side. The cross section of the SIP 101 in FIG. 4B shows the insulating layer 401 which is bounded by the frame and the first board 208 and the second board 209. In particular in FIG. 4B, the insulating layer 401 is sandwiched between each of the brace members 205. In the embodiment shown in FIG. 4B there is a plurality of brace members 205 and therefore the insulating layer 401 is disposed in sections between each of the brace members 205. If there were no brace members 205 in the SIP 101 then it could be appreciated that the insulating layer 401 may comprise a single section.

It is preferable that the insulating layer 401 is between 50 mm and 250 mm depending on the insulation requirements of the building 100. The insulating layer 401 may preferably comprise a mineral wool material although other suitable materials may be possible depending on their thermal resistance.

The insulating layer provides a substantial amount of the thermal resistance, although the first board 208 and the second board 209 can also provide a level of resistance. In theory, if each layer of the SIP 101 has the same cross sectional area, this may not be true as the frame 200 may not cover the entire cross sections area, then the total thermal resistance in parallel is found using this equation.

$R_{total} = {\frac{1}{\frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{3}}} = \frac{1}{\left( {\frac{k_{1}}{L_{1}} + \frac{k_{2}}{L_{2}} + \frac{k_{3}}{L_{3}}} \right)A}}$

Here the thermal resistance of each layer is R_(n), the thermal conductivity of each layer is k_(n), the thickness of each layer is L_(n) and the cross-sectional area is A. R_(total) is referred to as the ‘R’ value for the SIP 101, given in the unit m2K/W.

The amount of heat transfer per unit area and temperature difference can be found using this equation.

$U = \frac{1}{R_{total}}$

U can be referred to as the ‘U’ value of the SIP 101, given in the unit W/m2K.

The amount of heat transfer can be found using this equation.

$Q = {{{UA}\left( {T_{1} - T_{2}} \right)} = \frac{A\left( {T_{1} - T_{2}} \right)}{R_{total}}}$

The FRP frame 200 can significantly increase the thermal resistance over using a metal frame. This can significantly reduce the likelihood of thermal bridging. Thermal bridging is in which a particular area of a SIP 101 or wall 102 has a higher thermal conductivity than the surround area. This results in a path of least resistance in which the generally colder are from outside the building 100 transfers to the inside of the building 100. This can also result in ghosting which is when the poorly insulated area of the SIP 101 or wall 102 becomes colder on the inside of the building 100 and water vapour cools and condenses creating wet patch. As the FRP frame 101 has a lower thermal conductivity than a metal frame, the likelihood of thermal bridging occurring is much lower.

The first board 208 is generally positioned on the inside of the building 100. The first board 208 may further comprise an inner covering 404 applied to the outside of the first board 208. The inner covering 404 may comprise fire resistant material.

As shown in FIG. 4C, the SIP 101 may further comprise a fire resistant layer 406 which also comprises a fire resistant material. The fire resistant layer 406 is placed between the first board 208 and the insulating layer 401. The fire resistant layer 406 may provide an additional fire safety feature if the inner covering 404 became damaged from wear and tear on the inside of the building 100.

The fire resistant material may comprise an intumescent material such as soft or hard char. The fire safety rating for the SIP 101 is determined in accordance with BS476-21:1987 and BS476-7:1997

The second board 209 is generally positioned on the outside of the building 100. The second board 209 may further comprise an outer covering 405 applied to the outside of the second board 209. The outer covering 405 may comprise water resistant coating such as a silicone render.

The SIP 101 may further comprise an air gap 403 between the insulating layer 401 and the first board 208. The air gap 403 provides space for services such as water, gas and electrics. The air gap 403 is preferably between 10 mm and 50 mm depending on the insulation and service requirements of the building 100. The air gap 403 is preferably prefabricated offsite; however, it can be retrofitted onsite if additional services were required.

The services, windows and doors are preferably fitted to the SIP 101 offsite where it is cleaner and easy to fit. However, due to the flexibility of the SIP design, it is possible to retrofit the services, windows and doors onsite.

As mentioned above, the frame 200 may comprise a hollow cross section. The hollow cross section of the frame 200 may reduce the overall mass of the frame 200 while not significantly reducing the strength of the frame 200. The reduced mass of the frame 200 may ease the assembly process on site. The hollow cross section may also allow the frame 200 to be filled with an insulating filler 402. This can be the same material as the insulating layer 401 and may improve the overall insulating properties of the SIP 101.

FIG. 5 shows a SIP assembly 500. In particular, the SIPs 101 are coupled to each other vertically so that the first SIP 101 is on top of the second SIP 101. In the embodiment shown, the base member 201 of the first SIP 101 is coupled to the top member 202 of the second SIP 101. It is preferable that the first SIP 101 base member 201 and the second SIP 101 top member 202 are coupled to one another using an adhesive 207. However, it may also be possible for the frame 200 members to be coupled to one another using mechanical fastening means, such as screws, nails and nuts and bolts. Although, metal mechanical fastening means could be susceptible to rusting in moist conditions. The adhesive 207 may preferably comprise a two-part methacrylate adhesive, although any suitable adhesive for building construction may be used.

The SIP assembly 500 shown in FIG. 5 could represent a ground floor and first floor wall 102. The gap between the first board 208 and the second board 209 and the top and bottom of the frame 200 is shown on both SIPs 101. In this embodiment, the gap at the bottom of the ground floor SIP 101 could be used for attaching the flooring. The gap at the top of the ground floor SIP 101 could be used for attaching the ground floor ceiling and the first floor flooring. The gap at the top of the first floor SIP 101 could be used for attaching the first floor ceiling.

The brace members 205 of the first SIP 101 are shown to align with the brace members 205 of the second SIP 101. This can be used to effectively transfer the loading from one SIP 101 to another 101.

To assemble the building 100, first the SIPs 101 are prefabricated in a factory offsite. Secondly, the SIPs 101 are delivered to site in a “kit” preferably providing all of the materials to assemble the building 100. Thirdly, the SIPs 101 are lifted into place, generally using a crane. The assembly method starts at one corner of the ground floor of the building 100. The first corner provides a datum from which all of the other SIPs 101 are positioned relative to. The sequence of SIP 101 assemble is dependent on the particular building 100 design, however, it is preferable to assemble the building 100 one floor at a time. Once all of the SIPs 101 are in place for one floor then the ceiling and flooring trusses are fixed into place. When constructing a multiple storey SIP assembly 500, such as the one shown in FIG. 5 , temporary alignment boards may be used to help guide the SIPs 101 into place. This also helps to keep the SIPs 101 in the correct position until the adhesive 207 has set.

FIGS. 6A and 6B show a top view of a SIP assembly 500 in which two SIPs 101 are joined in a corner. The second side member 204 acts as a male element which is fits into the female element created between the first board 208 and the second board 209. The second board 209 of one SIP 101 extends along the end of the other SIP 101 so that the insulating layer 401 is protected from the outside environment. On the inside of the corner joint an internal gap 601 can be left between the first boards 208. This can allow for errors in the tolerances or thermal expansion of the SIPs 101. It is preferable that this gap is filled in on site using plaster or the same material as the inner covering 404.

In the top view shown in FIGS. 6A and 6B the brace members 205 and the insulating layer 401 are not visible as the top member 202 extends over the top of the brace members 205. FIGS. 7A and 7B show a cross section view of the corner joint in which the brace members 205 and the insulating layer 401 can be seen. In the corner, one of the SIPs 101 shows the brace member 205 butted against the second side member 204 whereas the other SIP 101 shows a gap between the brace member 205 and the first side member 203. Either of these configurations is possible and it is variable depending on the structural requirements for the building 100.

As shown in FIG. 7A, it is preferable that one of the SIPs 101 has a gap in the first board 208 so that the frame 200 of each SIP 101 can directly couple to one another. This can increase the overall strength of the joint as the frame is generally the primary load path. In this embodiment, the wider side of the second side member 204 couples to the narrower side of the first side member 203 and the brace member 205.

It is preferable that the first side member 203 of the first SIP 101 is coupled to the second side member 204 of the second SIP 101 using an adhesive 207. In this case, additional joint strength can be created by coupling the second side member 204 to the first side board 208 and the second side board 209. However, it may also be possible for the components to be coupled to one another using mechanical fastening means, such as screws, nails and nuts and bolts. Although, metal mechanical fastening means could be susceptible to rusting in moist conditions. The adhesive 207 may preferably comprise a two-part methacrylate adhesive, although any suitable adhesive for building construction may be used.

FIGS. 8A and 8B show a top view of a SIP assembly 500 in which two SIPs 101 are joined in a T section joint. The second side member 204 acts as a male element which is fits into the female element created between the first board 208 and the second board 209. On the inside of the T section joint corners an internal gap 601 can be left between the first boards 208. This can allow for errors in the tolerances or thermal expansion of the SIPs 101. It is preferable that this gap is filled in on site using plaster or the same material as the inner covering 404.

In the top view shown in FIGS. 8A and 8B the brace members 205 and the insulating layer 401 are not visible as the top member 202 extends over the top of the brace members 205. FIGS. 9A and 9B show a cross section view of the T section joint in which the brace members 205 and the insulating layer 401 can be seen. In the T section joint corners, the bottom SIP 101 shows the brace member 205 butted against the second side member 204 whereas the top SIP 101 shows a gap between the two brace members 205. It is possible for there to be no gap between the two brace members 205 in the top SIP 101 and it is variable depending on the structural requirements for the building 100.

As shown in FIG. 9A, it is preferable that the top SIP 101 has a gap in the first board 208 so that the frame 200 of each SIP 101 can directly couple to one another. This can increase the overall strength of the joint as the frame is generally the primary load path. In this embodiment, the wider side of the second side member 204 couples to the narrower side of the brace members 205.

FIGS. 10A and 10B show a top view of a SIP assembly 500 in which two SIPs 101 are joined in a double T section joint. The second side members 204 act as male elements which is fits into the female elements created between the first board 208 and the second board 209. On the inside of the double T section joint corners an internal gap 601 can be left between the first boards 208. This can allow for errors in the tolerances or thermal expansion of the SIPs 101. It is preferable that this gap is filled in on site using plaster or the same material as the inner covering 404.

In the top view shown in FIGS. 10A and 10B the brace members 205 and the insulating layer 401 are not visible as the top member 202 extends over the top of the brace members 205. FIGS. 11A and 11B show a cross section view of the double T section joint in which the brace members 205 and the insulating layer 401 can be seen. In the double T section joint corners, the bottom and top SIPs 101 show the brace member 205 butted against the second side member 204 whereas the middle SIP 101 shows a gap between the two brace members 205. It is possible for there to be no gap between the two brace members 205 in the middle SIP 101 and it is variable depending on the structural requirements for the building 100.

As shown in FIG. 11A, it is preferable that the middle SIP 101 has a gap in the first board 208 and the second board 209 so that the frame 200 of each SIP 101 can directly couple to one another. This can increase the overall strength of the joint as the frame is generally the primary load path. In this embodiment, the wider side of the second side members 204 couple to the narrower side of the brace members 205.

The illustrated embodiment, and the alternative embodiments that are described, only represent examples of how the ideas and concepts of the present disclosure can be implemented. Those skilled in the art will recognize that other embodiments for carrying out or practicing the ideas and concepts of the present disclosure are also possible. Modifications to illustrated embodiment, and to the alternative embodiments that are described, are possible without departing from the scope of the present disclosure as defined by the accompanying claims.

Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a nonexclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Each feature disclosed in the description, and, where appropriate, the claims and drawings may be provided independently or in any appropriate combination. 

1. A structural insulated panel, SIP, for a building, the SIP being attachable to another such SIP to provide a structure of the building, the SIP comprising: a frame; a first board attached to a first face of the frame; a second board attached to a second face of the frame; and an insulating layer bounded by the frame and the first and second boards, wherein the frame is fibre-reinforced plastic, FRP.
 2. The SIP according to claim 1, wherein the frame has a joining surface that faces away from the centroid of the SIP so as to be mateable with a joining surface of a frame of another such SIP.
 3. The SIP according to claim 2, wherein the joining surface extends around the entire perimeter of the SIP.
 4. The SIP according to claim 2, wherein the frame comprises: at least two edge members located at periphery of the SIP, at least one of the at least two edge members providing at least a part of the joining surface; and at least one brace member extending from one of the at least two edge members to another one of the at least two edge members to provide support to those edge members.
 5. The SIP of claim 4, wherein the at least part of the joining surface provided by the at least one edge member is flat, and preferably wherein the at least part of the joining surface provided by the at least one edge member is either perpendicular or parallel to the first and/or second face of the frame.
 6. The SIP according to claim 5, the at least two edge members comprise: a base member; a first side member; a second side member; and a top member.
 7. The SIP according to claim 6, wherein the brace member is parallel to the first side member and to the second side member optionally wherein the brace member is oblique to the first side member or the second side member.
 8. (canceled)
 9. The SIP according to claim 1, wherein the frame further comprises at least one bar member.
 10. The SIP according to claim 9, wherein the bar member is parallel to the base member and to the top member optionally wherein the first board is attached to the first face of the bar member and the second board is attached to the second face of the bar member.
 11. (canceled)
 12. The SIP according to claim 4, wherein the at least two edge members and/or the at least one brace member and/or the at least one bar member have a square or rectangular cross section optionally wherein the at least two edge members and/or the at least one brace member and/or the at least one bar member are hollow, and have a depth between 75 mm to 300 mm and a width between 25 mm to 200 mm.
 13. (canceled)
 14. The SIP according to claim 4, wherein the at least two edge members and/or the at least one brace member and/or the at least one bar member are joined to one another using adhesive.
 15. The SIP according to claim 1, wherein the frame is pultruded FRP.
 16. The SIP according to claim 1, wherein the first board and the second board do not extend the full height of the frame optionally wherein the SIP further comprises a flooring truss attached to the first face of the frame in the area not covered by the first board.
 17. (canceled)
 18. The SIP according to claim 1, wherein the first board and the second board each comprise a magnesium oxide board optionally wherein the first board and the second board are each between 3 mm to 25 mm thick, optionally wherein the first board and the second board each coupled to the frame using adhesive.
 19. (canceled)
 20. (canceled)
 21. The SIP according to claim 1, wherein the insulating layer comprises a non-combustible mineral wool, preferably wherein the insulating layer is between 50 mm to 250 mm thick.
 22. (canceled)
 23. The SIP according to claim 1, wherein the panel further comprises a fire resistant layer, the fire resistant layer is sandwiched between the frame and the first board optionally wherein the fire resistant layer comprises an intumescent material such as soft char or hard char.
 24. (canceled)
 25. The SIP according to claim 1, wherein the panel further comprises an outer covering, the outer covering is applied to the second board optionally wherein the outer covering comprises a water resistant material, such as a silicone render.
 26. (canceled)
 27. The SIP according to claim 1, wherein the panel further comprises an inner covering, the inner covering is applied to the first board optionally wherein the inner covering comprises a fire resistant material, such as soft char or hard char.
 28. (canceled)
 29. An SIP assembly, comprising the SIP according to claim 1 joined to another such SIP.
 30. The SIP assembly according to claim 29, wherein the SIPs are joined to one another at the joining surfaces using adhesive optionally wherein the adhesive comprises a two-part methacrylate adhesive.
 31. (canceled) 